Multiplex telegraphy



(No Model.)

'0.'SELDEN.

MULTIPLEX TELEGRAPHY.

No. 270,990. Patented Jan.28,1888.

N. PETERS. Photo-Lithographer, Washinglmn o z;

UNITED STATES.

CHARLES SELDEN,

PATENT ()FFICE.

OF TOLEDO, OHIO.

MULTIPLEX TELEGRAPHY.

SPECIFICATi0N forming part of Letters Patent No. 270,990, dated January-23, 1883. Application filed September 9, 1882. (No model.)

To all whom it may concern:

Be it known that I, CHARLES SELDEN, a citizen of the United States, and a resident of Toledo, in the county of Lucas and State of Ohio, have invented certain new and useful Improvements in Multiplex Telegraphs, of which the following is a specification.

My invention consists of certain novel combinations of apparatus, as hereinafter described and claimed, whereby two messages may be sent in each direction over the same 'wire without interfering with one another.

The drawing is a diagram illustrating the manner in which the various parts arecombined and connected.

T T indicate the two levers of the transmitting apparatus, each operated in the ordinary way by a local electro-magnet key and battery, K being the key for transmitter T and K the key for transmitter T These transmitters are suitably constructed and connected to one another and to the two sections M B M B of a main battery for the purpose of sending the following combination of currents: When both keys are at rest no current is to line. When K is depressed a current of positive polarity is sent to line. \Vhen K is depressed a current of the opposite polarity and approximately the same strength is sent to line. When both keys are depressed together a current of positive polarity and of a strength greater than that sent by either key is transmitted. instance the currentstrength is that of both main batteries. Transmitter T is provided with two sets of continuity-preserving transmitting-points, (indicated at a b,) each set consisting of the ordinary hook, spring normally resting against the hook, and stop arranged in the path of the spring, so that when thelever is operated the spring comes into contact with said stop and is simultaneously removed from contact with the hook. For the sake of simplicitythe stop will be termed the front and the hook the back contact. The transinittingpoints I) are suitably insulated from the set c in any well-known or desirable manner.-

Transmitter-lever T is provided with three sets of transmitting-points, c d e, the hooks and springs of all three sets being mounted thereon in any desired manner, and also suitably insulated.

1n the present The manner in which the various parts are connected will be best explained by detailing the path of the current in the various positions of the transmitters. Normally the parts are in the position shown and the contact between the spring and the book of every set of points a b c d e is closed. The circuit from the main line to earth is then through back contacts of a and 0 directly to earth. Both main batteries are disconnected, the front contacts at a and 0 being open. If transmitter T be operated by closing key K, main battery M B is put to line with a positive polarity, its circuit being through front contact at a. to

line, and through back contact at d, transmitter T to earth. The front contact at bis also closed; but no effect is produced thereby under these conditions.

When transmitter T is operated main battery M B is put to line with a negative polarity through front contact at 0 and back contact at a of transmitter T, which is under this condition supposed to be at rest. The opposite pole of the battery is connected to earth through back contactat b,transmitterT. The

back contacts at cl 0 are at the same time broken; but no effect is produced under this condition. When both keys are operatcd'together main batteries M B and M B both flow to line with a positive polarity through frontcontact at at, their other pole being connected to earth through the front contact at e, transmitter T and the front contact at b, transmitter T. The back contacts at d and b are at this operation both broken, thepurpose being to break both connections of wire 8 to earth, one of which connections-viz., back contact of b-is employed when battery M B alone is put to line by transmitter T ,'and the other of which-via, back contact of dis used when battery M B alone is put to line by the operation of transmitter T.

Other constructions and arrangements of transmitters and batteries might be used for producingthe above-described playof currents for use with the arrangement of receivers to be now described. As intimated, itis not necessary that the batteries M B M B should be of the same strength, although they are here so shown.

At the receiving end of the line,A A indicates a polarized relay of any desired construction, thearmature-lever of which is provided ,with a retracting-spring, G. This relay is adapted to respond to currents of positive polarity, and by overcoming the action of the retractor Grto close the points T T, thus com- 5 pleting the circuit of the local battery V,which operates the sounder U. Spring G is adjusted so that a current either from battery M B alone or from both batteries will close the contacts T T. ,A negative current will draw the armature in the other direction, and will assist spring Gin keeping the local circuit broken. B B indicates a second polarized relay, the armature-lever of which plays between two contact springs or levers, L L, which are I 5 adapted, as indicated, to close a shunt or short circuit for the local battery P when they are both in contact with connected stops K K. The relay-armature of B B is drawn into contact with lever L by the action of a negative current from battery M B, and separates said lever from contact-stop K, thus breaking the short circuit of the local battery P and cansing the sounder to operate. Its movement in so doing is opposed by spring D applied to z 5 the armature-lever, and by spring F applied to the spring or lever L, which springs are, however, so adjusted as to act only to restore the parts to their normal position with certainty, and are not suflicient to hold the re- 3 lay-armature against the action of its magnet when a negative current from battery M B alone is flowing to line.

When a positive current from battery M B flows to line the lever of B B is thrown in the 3 5 opposite direction and tends to separate the lespring E and thus cause a separation of L and K, so as to compel the currentof the local battery P to flow'in sounder M. The tension of spring E may, however, be made so great that, unassisted, the relay, even when acted 5 upon by the current from both batteries, would be able to overcome it. To allow this to be done, and to also provide a means of assisting the action of the relay-armature of B B when affected by the double positive current, (even 5-5 when retracting-spring E is adjusted below the tension of both batteries,) so as to secure promptitude and certainty of action, I propose to employ a supplemental relay, 0, which is by preference a neutral relay, but might be a polarized one, and which controls alocal magnet, O, so as to allow the latter to act at the proper times upon the lever L and assist the polarized relayB B in overcoming the retracting-spring E Forthis purpose I make the lever L the armature-lever of the local differentially-wound electro-magnet O, the circuit of one of whose differential coils passes, as

shown, through the contacts B B of the relay 0, while that of the other is constantly closed. Q represents the local battery, the current of which divides and passes through both coils of electro-magnet O in opposite directions so long as the contacts B R are closed. When the circuit through R R is broken the constantly-closed coil acts and the lever L is attracted against the action of its spring E so that a prompt and certain break of contact is effected at K. As will be readily understood, the retractor S for the neutral relay 0 is adjusted to such a strength that the contact R B can be broken only by both batteries M B MB Said relay is not affected bythe weaker current of positive main battery M B or negative main battery M B The method herein shown of controlling the local electro-magnet O, which assists the relay B B, is but one of many that might be adopted in practice. The relay 0 might act in many other ways well understood by those skilled in the art, so as to energize said electro-magnet when the relay-armature is drawn forward. It will be seen, however, that the above arrangement possesses the special advantage that the. magnet O is called into action the moment that the relay-armature of 0 begins to move. It is also to be noted that the energizing-coil on O, beingalways charged, is more ready to act with promptness when the circuit of the other coil is broken.

The general operation is as follows: When no current is upon the line the relay-contacts of A A are held broken by the action of spring G. Contacts B R are closed, and the armature-lever of B B is drawn against contact-lever L by 'spring D but not with sufficient force to overcome the strength of spring E The local of sounder U is therefore broken and local battery P is shunted from sounder M. When key K alone is closed battery M B flows to line with a positive current, which -closescontacts T T and sounder U responds.

Mis not atfected, because positive current from M B only is suflicient neither to separate points R B nor to remove lever L from its contact K. When key K alone is closed main battery M B flows to line with a negative'pola-rity, causing M to respond by breaking the connection between supplemental lever L and K. Contacts B R are not affected, the current not being of sufficient strength, and contacts T T remain open because the current is not of the proper polarity. When both keys are closed together both batteries M B M B flowto line with a positive polarity, and both sounders Uand M respond, the current being of IIO proper polarity to close contacts T T, and of proper strength, as well as polarity, to open contacts R R and to carry the lever of B B forcibly against supplemental lever L, so that the contact at K is broken by the combined action of the relay armature-lever and the 10- cal electro-magnet 0.

It is not regarded as necessary to show the sending and receiving apparatus complete at both ends of the line. By the use of differential relays, rheostats, and condensers arranged sothat the outgoing currents do not affect the home relays, two separate messages may be sent and two received all on the same line and at the same-instant of time.

While I have described the employment; ofa differential magnet, O, for assisting the relay B B, I do not limit myself to that arrangement exclusively. Magnet may be an ordinary local magnet, so connected that points R R, if broken, would shunt a local battery through it. I, however, deem the differential arrangement as shown and described the mostefficient.

That I claim as my invention isl. The combination, with a duplex or multiplex telegraph relay, of a contact-lever for breaking and closing the local circuit of a receiving-instrument, an electro-magnet in another local circuit for assisting the relay in operating the contact-lever, and a supplemental I relay controlling the circuits of said electromagnet, and adjusted in the manner described to render said magnet operative at the proper time to re-enforce the action of the first-named relay.

2. The combination, substantially as described, of two relays,-an electro-magnet in a local circuit controlled by one of said relays,;

and an armature-lever for said electro-magnet, having contact points and stops in the local circuit for the other relay, and arranged to be also operated by said latter relay. 1

3. The combination, substantially as described, of a polarized relay, a supplemental contact-lever, and retractile spring therefor, applied, in the manner described, to stop the movement of the armature-lever under the action of a current-strength corresponding to one transmitting-key, an electro-magnet acting upon the supplemental lever in conjunction with the relay, and a supplemental relay for controlling the local circuit containing said electro-magnet, adjusted to respond only to a current of a greater strength.

4.. The combination, substantially as described, of a polarized relay and armature-levertherefor, arranged to play between two supplemental levers, a retractor for one of said levers, adjusted below the strength of current corresponding to a current of one polarity, and ot' a strength ,corresponding to one transmitter, and a retractor for the other lever, ad-

justed above the strength of the current of the opposite polarity sent by the other transmitting-key alone, as and for the purpose described.

5. The combination, substantially as described, of two supplemental contact-levers, closing, when against their stops, the'short circuit'of a local battery, a polarized'relay-armature playing between said levers, retractors applied to said levers, so as to hold them in contact with their stops, and adjusted in the manner described with relation to one another, a local electro-magnet for acting upon the supplemental lever having the stronger retractor, and a supplemental relay controlling the local circuits for said electro-magnet.

6. The combination, substantially as described, with a supplemental contact-lever for one relay, of a differentially-wound local electro-magnet acting upon the same, and a secondrelay whose back contacts are in circuit with one of the coils of said electro-magnet.

7. The combination, substantially as described, of the polarized relay B B, having retractor D supplemental levers L L, with retractors adjusted to different strengths of current, a difi'erentially-wouud local electromagnet, 0, and a relay controlling the same, whose retractor is adjusted above the weaker of the retractors for the supplemental levers.

8. The combination, substantially as described, of two polarized relays, one of which is provided with a supplemental contact-lever, a supplemental relay controlling the circuit of an electro-magnet whose armature is attached to said supplemental lever, and transmitting apparatus adapted to send, when one key is depressed, a current of one polarity, when the other key isdepressed a current of the opposite polarity, and when both keys are depressed together a current of greater strength than that sent by either separately.

9. The combination of transmitters T T, having respectively two and'three sets of continuitypreserving transmitting points, two main batteries, M B M B, and connections, as shown and described, whereby said batteries may be placed to line singly, one with a positive and the other with a negative polarity, according to which key is operated, and may be placed both to line, so as to re-enforce one another when both keys are operated.

10. The combination, with a duplex or mul tiplex telegraph relay, of a contact-lever for controlling the local circuit of a receiving-instrument, an electro-magnet in a local circuit for assisting the relay in operating the contactlever, and means for rendering said electromagnet operative, adjusted, in the manner described, to bring the same into action at the proper time to re-enforce the action of the relily. o I

Signed at Toledo, in the county of Lucas and State of Ohio, this 15th day of August, A. D. 1882.

CHARLES SELDEN.

Witnesses: 7

ED. MOORE, JOHN M. WHEELER.

ICE .1 

